BVV3000 INFINIUM Trial

[agedhorse]

You said it was the 3.15A fuse that blew in post #1.

What is the fuse number and value?

You have consistently posted conflicting information than this thread, which makes me question everything you have been doing and do every assumption you have made so far.

Due to safety aspects, it’s somewhat concerning IMO and IME.

 

[agedhorse]

If you are pointing to F15 with your stick, that's a 0.315-T type fuse which is time lag and is used to protect the transformer from a failure in the screen supply. It MUST be a 315mA (not a 3.15A as you stated in post #1), and it won't open with a tube fault (single screen shorted to ground) for at least 10 seconds. If it opens within a couple of seconds, there is a fault within the supply itself.

Without the output tubes installed, if it still blows the fuse, it's guaranteed to be a supply fault.

The screen resistors must also be tested because IF you used a 3.15A fuse, it's possible (though not likely) that one or more of these might have been damaged.

There are a lot of things going on with that supply, and there are errors and/or missing information contained within the service docs, so you really do need to know what you are looking at before making ANY assumptions.

You can not use the Ampeg schematics, there are way too many difference to be useful (in spite of what internet lore might incorrectly suggest).

 

[Tim Payne]

If you are pointing to F15 with your stick, that's a 0.315-T type fuse which is time lag and is used to protect the transformer from a failure in the screen supply. It MUST be a 315mA (not a 3.15A as you stated in post #1), and it won't open with a tube fault (single screen shorted to ground) for at least 10 seconds. If it opens within a couple of seconds, there is a fault within the supply itself.

Without the output tubes installed, if it still blows the fuse, it's guaranteed to be a supply fault.

The screen resistors must also be tested because IF you used a 3.15A fuse, it's possible (though not likely) that one or more of these might have been damaged.

There are a lot of things going on with that supply, and there are errors and/or missing information contained within the service docs, so you really do need to know what you are looking at before making ANY assumptions.

You can not use the Ampeg schematics, there are way too many difference to be useful (in spite of what internet lore might incorrectly suggest).

 

[Tim Payne]

I was wrong about the fuse, this is a 315mA and not a 3.15A. Since I didn't use the latter anyway this is no cause for concern. I'd replaced the filter caps not longer after buying it as one of them had burst (metal top blown open).

Ran the amp earlier for about 20 minutes using the existing valves with no effect on the fuse although it was breaking up like the output valves were bad.

When the new valves arrive I'm just going to install these and see how it sounds.

 

[Tim Payne]

I was wrong about the fuse, this is a 315mA and not a 3.15A. Since I didn't use the latter anyway this is no cause for concern. I'd replaced the filter caps not longer after buying it as one of them had burst (metal top blown open).

Ran the amp earlier for about 20 minutes using the existing valves with no effect on the fuse although it was breaking up like the output valves were bad.

When the new valves arrive I'm just going to install these and see how it sounds.

*The fuse has T315mA 250v written on the silver caps*

 

[agedhorse]

Ok, good luck.

 

[Tim Payne]

Ok, good luck.

Thankyou

 

[Adriano Macedo]

Hi.
Got to get back to you guys about the bvv3000 as I think maybe it will help someone.

A few years ago, no more than one year after the warranty repair, the amp died again. Got some tips from Audio Repair Berlin and a friend of mine but it didn't work. Well, actually i also have an Alphabass and a protube4 so, the bugera remained in my basement until now. A few months ago got a crate tube combo for psu repair and that got me inspired to try to fix my amp.
Previously, my friend changed C75 as this is a common part that normally fails, although it looked good at the time. Also, R155 was good, measured outside the circuit, no change required. So i got the amp back and put it in my basement an forgot about it.

I thought i would try one last time, but this time i would try to fix it myself. Got the circuit out, all cables disconnected, tested resistance to all three transformers and they were good! Bulb tester in, driver tubes and power tubes out, preamp board and infinium boards disconnected. Test: filament transformer good with all voltages but no HT! All fuses are ok. So, partially, the psu was running the fans and the heater rails. Why the HT transformer was not getting the 220v from the mains input pcb (x49 / x44) ?? Looked at it and there is a relay not switching when i flipped power and standby... ok, the relay tested good so i thought it must be powered from somewhere else - x50. On the power amp there is only one elco, 4700uf/25v (C72) cap so there must be diodes involved there. Although the pcb is dark, i found out D67,D62,D67 and D66 + C72 were supposed to power the relay and transistors. Pulled all out, measured, and all looked good although C72 measured in my ESR atmega328 a little bit below 4700. Put it all back, all wires and cables connected, flipped standby, the relay clicked(?!) Now in with the tubes (original bugeras that came with the amp) and also OT, the bulb didn't like the tubes in so i had to power directly. And i finally got sound. After a few minutes, the infinium leds were doing their work, flashing randomly. Stared at them for a few minutes, random flashes and one led remained lit. Ok bad tube. Some minutes later, fault came in (red led), no sound, and instantly it flipped to orange again - like some owners and myself have always experienced. One hour later of testing and after several faults (with one infinium led always lit and plenty of random flashes of the other leds), powered down and changed C72 and the four diodes mentioned. Got 11,5v on x50 again. Relay clicked and got sound. After 10 minutes of playing some music, there was no infinium leds lit! So, no bad tube! Stared at them from time to time and after 4 hours the leds do flash randomly in a different way, very instantly.

Hope it remains strong as it sounds so good.

regards,

 

[agedhorse]

That would be an amazingly lucky repair, replacing good parts with good parts and it suddenly starts working. Perhaps there was something else going on?

 

[Adriano Macedo]

That is what i thought when i desoldered and resoldered those parts, and it doesn't make sense. So the only thing i could think of was some cold joint in that zone and the 4700uf/25 being a little off. And that kept me thinking and i tried to measure the parts again.
As i said earlier forward-biased on all four diodes was fine and in reverse all presented OL too. In with the ESR this morning and one was presented as dead(?!). The other three showed reasonable values. On further analysis (with lens) to this particular diode, although both legs were firmly attached to cathode and anode, now with the MM and some alligator clips and jiggling a bit the legs, it showed intermittent readings. So when i resoldered it the faulty leg made the connection again but intermittently, powering of and on the relay.
Finally found it. Bad diode.

 

[agedhorse]

The cap can be off by 50% and it won't make a difference.

Identifying cause of the fault makes the actual repair much easier and less time consuming.

 

[Adriano Macedo]

Thanks. Just wanted to share my findings if someone runs into something similar.

 

[agedhorse]

Thanks. Just wanted to share my findings if someone runs into something similar.

That's a very unusual (and random, like 1 in a million) failure, but I can see everybody rushing to repair their amps by replacing those parts even if they are entirely unrelated to their symptoms just because they read about it on the internet.

Oh, and speaking of the internet, Ivermectin prices are still up due to the run on the product during COVID when it was touted online as a miracle cure... Grrrr.